http-push: do not access git_default_email directly

By calling the ident_default_email accessor, we can be sure
that the default value is actually filled-in.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -904,7 +904,7 @@ static struct remote_lock *lock_remote(const char *path, long timeout)
 		ep = strchr(ep + 1, '/');
 	}
 
-	escaped = xml_entities(git_default_email);
+	escaped = xml_entities(ident_default_email());
 	strbuf_addf(&out_buffer.buf, LOCK_REQUEST, escaped);
 	free(escaped);